The present invention relates to a three-piece solid golf ball. More particularly, it relates to a three-piece solid golf ball having excellent flight performance and good shot feel when hit by a driver, and excellent controllability and good shot feel when hit by an iron club.
Many types of golf balls are commercially selling, but two-piece solid golf balls and thread wound golf balls are generally used during rounds of golf. The two-piece solid golf ball, when compared with the thread wound golf ball, has better durability and better flight performance because of larger initial velocity when hitting and longer flight distance. Therefore, the two-piece solid golf ball is generally approved of or employed by many golfers. On the other hand, the two-piece solid golf ball has poor shot feel at the time of hitting an poor controllability or approach shots because of a lower spin rate.
In order to provide a two-piece solid golf ball having shot feel and controllability as good as the thread wound golf ball, a soft type two-piece solid golf ball using a softer core or cover has been proposed. However, the use of the soft core or soft cover adversely affects rebound characteristics, thus resulting, in the reduction of flight distance and the deterioration of durability.
It has also been proposed that an intermediate layer be placed between the core d the cover of the two-piece solid golf ball to maintain a balance between flight performance and shot feel at the time of hitting to maintain controllability (such as Japanese Patent Kokai Publication No. 142228/1994, Japanese Patent Kokai Publication No. 322962/1996, Japanese Patent Kokai Publication No. 239068/1997). These golf balls adopt a three-piece structure in which the hardness or hardness distribution of a core, an intermediate layer and a cover is maintain without a proper range, to obtain shot feel and controllability similar to the thread wound golf ball. For example, Japanese Patent Kokai Publication No. 142228/1994 suggests a three-piece solid golf ball which comprises a two-layered core consisting of an inner core and an outer core, and a cover covering the core. The outer core has a Shore D hardness of 30 to 50 and a flexural modulus of 200 to 400 MPa, and the cover has a Shore D of 55 to 68 and a flexural modulus of 200 to 450 MPa. However, since the cover is harder than the intermediate layer (the outer core) in the golf ball, it has poor controllability.
Japanese Patent Kokai Publication No. 322962/1996 suggests a three-piece solid golf ball which comprises a core and a two-layered cover consisting of an inner cover and an outer cover. The core has a deformation amount of 3.5 to 6.5 mm when applying an initial load of 10 kgf to a final load of 130 kgf, the inner cover has a flexural modulus of 3,500 to 6,000 kgf/cm2, the outer cover has a flexural modulus of 2,300 to all 5,500 kgf/cm2, and the flexural modulus of the outer cover is lower by 50 kgf/cm2 than that of the inner cover. In the golf ball, the outermost layer is made softer in order to improve the controllability. However, the cover is not sufficiently soft to improve the controllability, and the hardness of the core is not controlled to a proper range, and thus shot feel is poor.
Japanese Patent Kokai Publication No. 239068/1997 suggests a three-piece solid golf ball which comprises a core, an intermediate layer and a cover. The core has a JIS-C center hardness of not more than 75 and a JIS-C surface hardness of not more than 85, the hardness of the intermediate layer is higher than that of the surface of the core by not more than 5, and the hardness of the cover is lower than that of the intermediate layer by not more than 5. However, since the golf ball has a hardness difference between the center of the core and the surface of the core, the deformation amount is large, and thus shot feel and controllability are poor.
It is required to solve the above problem and provide a three-piece golf ball having better flight performance, better shot feel and better controllability.
A main object of the present invention is to provide a three-piece solid golf ball having excellent flight performance and good shot feel when hit by a driver, and excellent controllability and good shot feel when hit by an iron type club.
According to the present invention, the object described above has been accomplished by adjusting a hardness distribution and a deformation amount of the core when applying an initial load of 10 kgf to a final load of 130 kgf, and a hardness and specific gravity of the intermediate layer and cover to specified ranges, thereby providing a three-piece solid golf ball having excellent flight performance and good shot feel when hit by a driver, and excellent controllability and good shot feel when hit by an iron type club.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.